1、swap分区管理
- 用磁盘创建swap分区
[root@centos7 ~]#gdisk /dev/sdb ---创建分区，并把code改成8200
[root@centos7 ~]#lsblk ---分区创建完毕
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 50G 0 part /
├─sda3 8:3 0 50G 0 part /app
├─sda4 8:4 0 512B 0 part
└─sda5 8:5 0 2G 0 part [SWAP]
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 2G 0 part
sdc 8:32 0 150G 0 disk
├─sdc1 8:33 0 10G 0 part
├─sdc2 8:34 0 5G 0 part
└─sdc3 8:35 0 1K 0 part
sdd 8:48 0 120G 0 disk
sr0 11:0 1 7.7G 0 rom /run/media/root/CentOS 7 x86_64
[root@centos7 ~]#mkswap /dev/sdb1 ---创建swap文件系统
Setting up swapspace version 1, size = 2097148 KiB
no label, UUID=e32dc38a-b7cf-425d-b27c-0b99c4af4592
[root@centos7 ~]#vim /etc/fstab ---更改配置文件
1
2 #
3 # /etc/fstab
4 # Created by anaconda on Fri Jul 14 11:16:04 2017
5 #
6 # Accessible filesystems, by reference, are maintained under '/dev/disk'
7 # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
8 #
9 UUID=e7e1738b-58ae-49d3-9f7e-c62988ead392 / xfs defaults 0 0
10 UUID=348930fe-f95e-40e6-90ff-83c66b3f2e9a /app xfs defaults 0 0
11 UUID=dfbab032-681e-4e34-a16e-2f5e1eda5f32 /boot xfs defaults 0 0
12 UUID=6145ae5c-6ebd-4655-a52f-e90f9b5a9e58 swap swap defaults 0 0
[root@centos7 ~]#swapon -a ---激活交换分区
[root@centos7 ~]#cat /proc/swaps ----查看swap分区
Filename Type Size Used Priority
/dev/sda5 partition 2097148 0 -1
/dev/sdb1 partition 2097148 0 -2
[root@centos7 ~]#swapon -s ---查看swap分区
Filename Type Size Used Priority
/dev/sda5 partition 2097148 0 -1
/dev/sdb1 partition 2097148 0 -2
[root@centos7 ~]#vim /etc/fstab ---修改优先级，值在0-32767之间，值越大优先级越高，因为/dev/sdb1为sdb磁盘的第一个分区，是在外道，速度比较快，所以尽量先使用sdb1的swap分区
1
2 #
3 # /etc/fstab
4 # Created by anaconda on Fri Jul 14 11:16:04 2017
5 #
6 # Accessible filesystems, by reference, are maintained under '/dev/disk'
7 # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
8 #
9 UUID=e7e1738b-58ae-49d3-9f7e-c62988ead392 / xfs defaults 0 0
10 UUID=348930fe-f95e-40e6-90ff-83c66b3f2e9a /app xfs defaults 0 0
11 UUID=dfbab032-681e-4e34-a16e-2f5e1eda5f32 /boot xfs defaults 0 0
12 UUID=6145ae5c-6ebd-4655-a52f-e90f9b5a9e58 swap swap defaults 0 0
13 UUID=e32dc38a-b7cf-425d-b27c-0b99c4af4592 swap swap pri=10 0 0
[root@centos7 ~]#swapoff /dev/sdb1 ---先禁用
[root@centos7 ~]#swapon -s
Filename Type Size Used Priority
/dev/sda5 partition 2097148 0 -1
[root@centos7 ~]#swapon -a ---再激活
[root@centos7 ~]#swapon -s ---最后才能生效
Filename Type Size Used Priority
/dev/sda5 partition 2097148 0 -1
/dev/sdb1 partition 2097148 0 10
- 用文件创建swap分区
[root@centos7 ~]#fdisk /dev/sdc ---创建一个独立的分区
[root@centos7 ~]#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 50G 0 part /
├─sda3 8:3 0 50G 0 part /app
├─sda4 8:4 0 512B 0 part
└─sda5 8:5 0 2G 0 part [SWAP]
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 2G 0 part [SWAP]
sdc 8:32 0 150G 0 disk
└─sdc1 8:33 0 20G 0 part ---一个20G的独立分区创建完毕
sdd 8:48 0 120G 0 disk
sr0 11:0 1 7.7G 0 rom /run/media/root/CentOS 7 x86_64
[root@centos7 ~]#mkfs.xfs /dev/sdc1 ---创建文件系统
[root@centos7 ~]#mkdir /mnt/sdc1
[root@centos7 ~]#mount /dev/sdc1 /mnt/sdc1 ---把文件系统挂载到目录下
[root@centos7 ~]#df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 52403200 15338292 37064908 30% /
devtmpfs 485268 0 485268 0% /dev
tmpfs 499980 88 499892 1% /dev/shm
tmpfs 499980 7292 492688 2% /run
tmpfs 499980 0 499980 0% /sys/fs/cgroup
/dev/sda3 52403200 540240 51862960 2% /app
/dev/sda1 1038336 172284 866052 17% /boot
tmpfs 100000 12 99988 1% /run/user/0
ev/sr0 8086368 8086368 0 100% /run/media/root/CentOS 7 x86_64
▽dev/sdc1 20961280 32944 20928336 1% /mnt/sdc1
[root@centos7 ~]#cd /mnt/sdc1 ---进入这个目录
[root@centos7 sdc1]#dd if=/dev/zero of=swapfile bs=1M count=1024 ---创建一个大的文件，将来作为swap分区使用
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 13.2999 s, 80.7 MB/s
[root@centos7 sdc1]#mkswap swapfile ---创建swap文件系统
Setting up swapspace version 1, size = 1048572 KiB
no label, UUID=45d3ea5d-fac8-4cbe-9588-210d999a7802
1
2 #
3 # /etc/fstab
4 # Created by anaconda on Fri Jul 14 11:16:04 2017
5 #
6 # Accessible filesystems, by reference, are maintained under '/dev/disk'
7 # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
8 #
9 UUID=e7e1738b-58ae-49d3-9f7e-c62988ead392 / xfs defaults 0 0
10 UUID=348930fe-f95e-40e6-90ff-83c66b3f2e9a /app xfs defaults 0 0
11 UUID=dfbab032-681e-4e34-a16e-2f5e1eda5f32 /boot xfs defaults 0 0
12 UUID=6145ae5c-6ebd-4655-a52f-e90f9b5a9e58 swap swap defaults 0 0
13 UUID=e32dc38a-b7cf-425d-b27c-0b99c4af4592 swap swap pri=10 0 0
14 UUID=45d3ea5d-fac8-4cbe-9588-210d999a7802 swap swap default 0 0 ---修改配置文件
[root@centos7 sdc1]#swapon -a ---激活分区。有以下提示，建议把权限修改为0600
swapon: /mnt/sdc1/swapfile: insecure permissions 0644, 0600 suggested.
[root@centos7 sdc1]#chmod 0600 swapfile ---修改权限
[root@centos7 sdc1]#ll ---权限被更改
total 1048576
-rw-------. 1 root root 1073741824 Aug 9 20:17 swapfile
[root@centos7 sdc1]#swapon -s 分区创建成功
Filename Type Size Used Priority
/dev/sda5 partition 2097148 0 -1
/dev/sdb1 partition 2097148 0 10
/mnt/sdc1/swapfile file 1048572 0 -2
2、创建ISO文件
cd /app
mkdir centos6
cd centos6/
cp -r /media/CentOS_6.9_Final/.* . ---先将点打头的文件复制过来
cp -r /media/CentOS_6.9_Final/* . ---centos6.9第一张盘
cp -r /media/CentOS_6.9_Final/* . ---centos6.9第二张盘
mkisofs -r -o /app/CentOS-6-x86_64-Everything-0809.iso /app/centos6/ ----把目录里的内容制作成iso镜像文件,此时制作的ISO文件不能做为启动使用，只能用于yumf源。
[root@centos6 app]#rz ---上传mkdvdiso.sh脚本
[root@centos6 app]#ls
mkdvdiso.sh
[root@centos6 app]#chmod a+x mkdvdiso.sh
[root@centos6 app]#./mkdvdiso.sh --help ---查帮助
Error: /usr/bin/implantisomd5 Not Found!
Please install isomd5sum and try again.
[root@centos6 app]#yum search isomd5sum ---搜索安装包
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
centos6 | 4.0 kB 00:00 ...
==================== N/S Matched: isomd5sum =====================
isomd5sum-devel.i686 : Development headers and library for using
: isomd5sum
isomd5sum-devel.x86_64 : Development headers and library for
: using isomd5sum
isomd5sum.x86_64 : Utilities for working with md5sum implanted in
: ISO images ---为这个安装包
Name and summary matches only, use "search all" for everything.
yum install isomd5sum
./mkdvdiso.sh /app/centos6/ /app/CentOS-6-x86_64-Everything-0809-used.iso ---执行这个脚本可以将目录中的内容做成启动功能的iso文件，与mkisofs命令不同的是，源在前，目标在后
3、一些常用的小工具
- free
[root@centos6 cd]#free ---默认以k为单位
total used free shared buffers cached
Mem: 1004112 819232 184880 3280 73812 347900
-/+ buffers/cache: 397520 606592
Swap: 2097148 0 2097148
[root@centos6 cd]#free -m
total used free shared buffers cached
Mem: 980 800 180 3 72 339
-/+ buffers/cache: 388 592
Swap: 2047 0 2047
[root@centos6 cd]#free -g
total used free shared buffers cached
Mem: 0 0 0 0 0 0
-/+ buffers/cache: 0 0
Swap: 1 0 1
[root@centos6 cd]#free -h
total used free shared buffers cached
Mem: 980M 800M 180M 3.2M 72M 339M
-/+ buffers/cache: 388M 592M
Swap: 2.0G 0B 2.0G
[root@centos7 app]#free ---在centos7中都是给计算好的
total used free shared buff/cache available
Mem: 2048540 547780 1038912 14160 461848 1390260
Swap: 2097148 0 2097148
总结：buffers和cached都是缓存，前面的是元数据的缓存，后面的是数据的缓存，缓存里的内容可以清除，实际上用掉的内存为800-（72+339）=338 剩余的内存为180+（72+339）=592。
- df
文件系统空间占用等信息的查看工具：
df[OPTION]... [FILE]...
-H 以1000为单位
-T 文件系统类型
-h: human-readable
-i：inodesinstead of blocks
-P: 以Posix兼容的格式输出 ---假如前面设备名比较长，造成不和后面的同行，可以使用-p选项，让他们在一行
[root@centos6 app]#df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 50264772 4750828 42953944 10% /
tmpfs 502056 76 501980 1% /dev/shm
/dev/sda3 40185208 1097616 37039592 3% /app
/dev/sda1 991512 34904 905408 4% /boot
/dev/sdb1 10194676 23420 9646736 1% /home
/dev/sr0 6049912 6049912 0 100% /media/CDROM
/app/cenos6.9everyting-asddgggghhsds.osaddgdh
999320 1284 945608 1% /mnt/f1
[root@centos6 app]#df -P
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/sda2 50264772 4750828 42953944 10% /
tmpfs 502056 76 501980 1% /dev/shm
/dev/sda3 40185208 1097616 37039592 3% /app
/dev/sda1 991512 34904 905408 4% /boot
/dev/sdb1 10194676 23420 9646736 1% /home
/dev/sr0 6049912 6049912 0 100% /media/CDROM
/app/cenos6.9everyting-asddgggghhsds.osaddgdh 999320 1284 945608 1% /mnt/f1
- du
查看某目录总体空间占用状态：
du [OPTION]... DIR ---只统计目录的大小，以k为单位
-h: human-readable
-s: summary ---只统计目录的总大小，不单独统计里面的子目录。
[root@centos6 app]#du -sh /* ---统计根下的一级子目录的大小
- dd
[root@centos6 app]#echo abcdefg >f1
[root@centos6 app]#echo 123456789 >f2
[root@centos6 app]#ls
f1 f2
[root@centos6 app]#cat f1 f2
abcdefg
123456789
[root@centos6 app]#dd if=f1 of=f2 bs=1 count=2 skip=3 seek=4 conv=notrunc ---skip=3表示跳过读入的文件的前三个字节；seek=4表示跳过输出到的文件的前四个字节，从第5个字节处开始输入，conv=notrunc表示不截断
2+0 records in
2+0 records out
2 bytes (2 B) copied, 0.000318369 s, 6.3 kB/s
[root@centos6 app]#cat f1 f2
abcdefg
1234de789
[root@centos6 app]#dd if=f1 of=fA conv=ucase ---表示把小写转换成大写
0+1 records in
0+1 records out
8 bytes (8 B) copied, 0.000174666 s, 45.8 kB/s
[root@centos6 app]#cat fA
ABCDEFG
[root@centos6 app]#dd if=fA of=fa conv=lcase --大写转换成小写
0+1 records in
0+1 records out
8 bytes (8 B) copied, 0.000171626 s, 46.6 kB/s
[root@centos6 app]#cat fa
abcdefg
dd if=/dev/urandom of=/dev/sda1---x销毁磁盘数据
dd if=/dev/sda of=/dev/sda ---修复磁盘
[root@centos6 app]#dd if=/dev/zero of=f3 bs=1M count=1024 ---测试磁盘的写速度
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 5.35934 s, 200 MB/s
[root@centos6 app]#dd if=/app/f3 of=/dev/null bs=1M count=1024 ---测试磁盘的读速度
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 3.03901 s, 353 MB/s
总结：/dev/zero和/dev/null都是内存中的数据，读和写的时候很快。通过从文件中读写到/dev/null可以测磁盘的读速度；通过从/dev/zero读写到文件中可以测磁盘的写速度。